Shells in CO$_2$ Clusters

TL;DR

This study analyzes the abundance spectra of CO₂ clusters up to 500 molecules, revealing universal stability patterns, shell closures, and packing order, and highlights how small energy variations significantly affect cluster abundance.

Contribution

It introduces a comprehensive analysis of CO₂ cluster stability and structure, identifying shell closures and packing order using the evaporative ensemble framework.

Findings

Universal stability patterns across different expansion conditions

Identification of shell and subshell closing sizes

Confirmation of cuboctahedral packing ordering for large clusters

Abstract

Abundance spectra of (CO$_2$)$_N$ clusters (up to $N \approx$ 500) acquired under a wide range of adiabatic expansion conditions are analyzed within the evaporative ensemble framework. Analysis reveals that cluster stability functions display strikingly universal patterns for all expansion conditions. These patterns reflect the inherent properties of individual clusters. From this analysis the size-dependent cluster binding energies are determined, shell and subshell closing sizes identified, and cuboctahedral packing ordering for sizes above $N \approx 130$ is confirmed. It is demonstrated that a few percent variation in the dissociation energies translates into significant abundance variations, especially for the larger clusters.